Admiralty House is the official Sydney residence of the Governor-General of Australia. It is located in the suburb of Kirribilli, on the northern foreshore of Sydney Harbour (adjacent to Kirribilli House, which is the Sydney residence of the Australian Prime Minister). This large, Italianate, sandstone mansion occupies the tip of Kirribilli Point. Once known as "Wotonga", it has commanding views across Sydney Harbour to the Sydney Harbour Bridge and the Sydney Opera House. 

Its current name originates in the fact that it served as the residence for the Commander-in-Chief of the Royal Navy's Australia Squadron from 1885 to 1913. 

The original building on the site was completed, as a private dwelling, in mid-to-late 1843, by John George Nathaniel Gibbes, the then Collector of Customs for New South Wales and a member of the New South Wales Legislative Council. A portrait of Gibbes, painted in 1808, hangs in the house.  http://en.wikipedia.org/wiki/Admiralty_House,_Sydney